With no wind, a corn field in full sunlight will become CO2 limited in just 10 minutes or so.

That’s fascinating. How do you know? (Research? Personal experience?)

I was told that, but I can't find a link for that specific claim. However, I can find a link to some old research that shows CO2 falling during the day in low wind:

https://joannenova.com.au/2013/09/plants-suck-half-the-co2-o...

Thanks for digging that up. Looks very interesting.

This suggests using a greenhouse to absorb CO2 to keep the air you breath fresher.

To absorb CO2 at night, plants using the CAM photosynthetic system could be used. These plants absorb CO2 at night for use during the day, storing the CO2 temporarily as malate.

https://en.wikipedia.org/wiki/Crassulacean_acid_metabolism